Stamping arrangement and use thereof

ABSTRACT

In a stamping arrangement, during stamping a stamping punch makes contact, in the region of a punch shoulder, with a holding plate or a pressure plate between the stamping punch and holding plate. The stamping punch has a punch head and the holding plate has a receptacle for the punch head. Means for fastening the punch head to the holding plate have a pocket made in the punch head, a clamping screw screwed into a threaded bore of the holding plate, a pressure piece arranged in the axial direction of the clamping screw between the latter and the pocket, and a holding screw for the pressure piece, wherein the holding screw passes through a bore of the clamping screw and is screwed with a threaded portion into a threaded bore of the pressure piece. With the clamping screw in a screwed-in position, areal contact is made, on a side of the pocket that faces away from the punch shoulder, between a conical portion of the pressure piece and a conical portion of the pocket, and the punch shoulder bears against the holding plate or the pressure plate, wherein a screw head of the holding screw is arranged with axial play with respect to the clamping screw.

CROSS REFERENCE TO RELATED APPLICATIONS

This United States non-provisional application is the national stage ofInternational Application No. PCT/EP2014/002241 filed on Aug. 15, 2014,which claims the benefit of priority to European Application No. EP13181503.7 filed on Aug. 23, 2013, the entire disclosures of which areincorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a stamping arrangement having a stamping punchand a holding plate for the stamping punch.

BACKGROUND OF THE INVENTION AND RELATED ART

Stamping punches are used in so-called “prog dies” and “multiple diepresses”. Tools of this type work as sets comprising, in somecircumstances, a plurality of sister tools in multiple-die presses withhigh punching force.

The main field of application of such punching tools is automobileconstruction, in particular the construction of chassis and bodywork.

A “prog die” of this type, of small to medium size, has externalmeasurements of about 1,600 mm×1,200 mm, comprising a multiplicity offorming punches, for instance about 20 forming punches. In this case,stamping punches are generally arranged spatially close together,surrounded by piping which serves to monitor the pressures of installedgas pressure springs by means of manometers built into the tool.

As a result of the ever more advancing use of high-strength sheets inautomobile construction, the necessary stamping pressures, and thus alsothe stripping forces which act on the stamping punch and the anchoragethereof in its holding plate in the return and thus stripping operation,are increasing. In this context, a maximum load of these strippingforces of about 100 kN (10 tonnes) per forming punch can reasonably beassumed for the “prog die”. A stamping force of 1,000 kN (100 tonnes) isherein adopted as the basis. A stamping punch absorption system which isto be designed for this particular application must be able to absorbthese tensile forces in the return or stripping operation withappropriate certainties.

A significantly reduced working life of the arrangement is obtained if aplay-afflicted mounting of the stamping punch in the holding plate inthe return or stripping operation has to be registered. In this case,very high bending and gravitational forces act on the connection ofstamping punch and holding plate.

Furthermore, regard must be paid to the spatial relationships in thetool. The possibility must be given of being able to change the stampingpunches in the cramped lateral working space brought about by thearrangement. In particular, this should be possible quickly and withoutremoval of the holding plate in the event of wear or breakage of thepunch.

OBJECT AND SUMMARY OF THE INVENTION

The object of the present invention is to provide a stamping arrangementin which the working life of the arrangement, due to a play-freemounting of the stamping punch in the holding plate in the return orstripping operation, is significantly high.

The object is achieved by a stamping arrangement which is configuredaccording to the features of the invention disclosed herein.

The stamping arrangement according to the invention has a stamping punchand a holding plate for the stamping punch, wherein the stamping punch,in a stamping stroke, makes contact in the region of a punch shoulderwith the holding plate, or with a pressure plate disposed between thestamping punch and the holding plate. The stamping punch has a punchhead and the holding plate has a receptacle for the punch head. Inaddition, means for fastening the punch head to the holding plate areprovided. These means have according to the invention:

-   -   a pocket made in the punch head,    -   a clamping screw screwed into a threaded bore of the holding        plate,    -   a pressure piece arranged in the axial direction of the clamping        screw between the latter and the pocket,    -   a holding screw for the pressure piece, wherein the holding        screw passes through a bore of the clamping screw and is screwed        with a threaded portion into a threaded bore of the pressure        piece.

In this case, in a screwed-in position of the clamping screw, on a sideof the pocket that is facing away from the shoulder, a conical portionof the pressure piece makes full-faced contact with a conical portion ofthe pocket. In this screwed-in position of the clamping screw, the punchshoulder bears against the holding plate or the pressure plate, and ascrew head of the holding screw is arranged with axial play with respectto the clamping screw.

In this configuration of the stamping arrangement, in particular of themeans for fastening the punch head to the holding plate, it is ensuredthat the stamping punch is pretensioned with its punch shoulder in aplay-free manner against the holding plate or the pressure plate. In thestamping stroke, it is thus ensured that the stamping forces aretransmitted between punch shoulder and holding plate or punch shoulderand pressure plate. The stamping pressure is thus not absorbed by thepressure piece. Related to the return stroke or stripping operation ofthe stamping punch, this has the result that the holding plate and thestamping punch are moved in a play-free manner, since this freedom fromplay is guaranteed by the inventive design and arrangement of thepressure piece. There is thus no play-afflicted connection presentbetween holding plate and stamping punch and it is ensured that no looseconnection between holding plate and stamping punch arises. A looseconnection of this kind, which brings about an imprecise guidance of thestamping punch, would result in the stamping punch deforming or damagingthe stamped sheet in the course of the return stroke or strippingoperation. Apart from this, a play-afflicted connection of this kindleads to increased mechanical load upon the connection region of holdingplate and stamping punch, resulting in a shorter working life. Inparticular, there is the danger of the stamping punch breaking in theregion of the punch head.

Since the pressure piece does not make contact with a recess in thepunch head, which recess passes fully through the punch head, butinstead a pocket is provided in the punch head, increased forces can betransmitted via the punch head in the course of the return stroke orstripping operation.

In the stamping arrangement according to the invention, by means of theclamping screw, via the pressure piece, such a pretensioning can begenerated between punch shoulder and holding plate or pressure plate,which pretensioning guarantees that the stamping punch, following atheoretically possible setting operation, is still firmly seated andthus no play can arise between punch shoulder and holding plate orpressure plate.

In order that the stamping punch can be removed, it is necessary to pullthe pressure piece wedged in the pocket out of this pocket. This isrealized on the basis of the inventively provided connection which theholding screw establishes between the clamping screw and the pressurepiece. If the clamping screw is turned in the unscrewing direction, thisleads to the axial play between the screw head in the holding screw andthe clamping screw being reduced until the screw head of the holdingscrew bears against the clamping screw, and then, upon furtherunscrewing of the clamping screw, due to the form closure between thescrew head of the holding screw and the clamping screw, the pressurepiece is jointly moved, out of the clamping position with respect to thepocket.

Preferably, means for orienting the pressure piece in a rotationaldirection of the pressure piece relative to the conical portion of thepocket are provided. As a result, a loose precentering of the pressurepiece is guaranteed, whereby it can be readily ensured that, upon theadvancement of the clamping screw, the conical portion of the pressurepiece makes full-faced contact with the conical portion of the pocket.

According to one embodiment, it is provided that the describedarrangement for holding the stamping punch in the holding plate isdoubly provided. Thus two pockets are made in the punch head, and apressure piece cooperates with the respective pocket, and a clampingscrew and a holding screw cooperate with the pressure piece. In thisrespect, reference is made to the preceding statements. In this case, inparticular these pockets are identically configured, also these clampingscrews are identically configured, also these pressure pieces areidentically configured, and finally these holding screws are identicallyconfigured.

The stamping arrangement according to the invention is used, inparticular, in a “prog die” or multiple die press, having a multiplicityof stamping and/or pressing tools, with a stripping force >50 kN, inparticular in a multiple die press with a stripping force up to 100 kN.

Further features of the stamping arrangement according to the inventionare shown and described hereafter in the description of exemplaryembodiments of the invention, the accompanying drawing figures and thedescription of the drawing figures, wherein it is noted that allindividual features and all combinations of individual features are tobe considered various aspects and embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

In the accompanying drawing figures, the invention is represented on thebasis of various exemplary embodiments when used in a “prog die”,without the invention being restricted to these embodiments and use, andwherein like reference character in the various figures represent likeor similar parts.

FIG. 1 represents a top view of a “prog die” fitted with a multiplicityof forming punches, of which three are stamping arrangements accordingto a first exemplary embodiment the invention.

FIG. 2 represents a stamping arrangement according to the invention in athree-dimensional view.

FIG. 3 represents the stamping arrangement according to FIG. 2 in anexploded representation.

FIG. 4 represents the stamping arrangement according to FIG. 2 in a viewIV in FIG. 5.

FIG. 5 represents the stamping arrangement in a view V in FIG. 4.

FIG. 6 represents a section through the stamping arrangement accordingto the line VI-VI in FIG. 4.

FIG. 7 represents the region A according to FIG. 6 in enlargedrepresentation, wherein in FIG. 7 a pressure piece of the stampingarrangement is illustrated in its clamping position.

FIG. 8 represents a section according to FIG. 7, illustrated with thepressure piece of the stamping arrangement having been moved out of apocket.

FIG. 9 represents a holding plate of the stamping arrangement in athree-dimensional view.

FIG. 10 represents the holding plate in a view X according to FIG. 11.

FIG. 11 represents the holding plate in a view XI according to FIG. 10.

FIG. 12 represents the holding plate in a view XII according to FIG. 11.

FIG. 13 represents a stamping punch of the stamping arrangement in athree-dimensional view.

FIG. 14 represents the stamping punch in a view XIV according to FIG.15.

FIG. 15 represents the stamping punch in a view XV according to FIG. 14.

FIG. 16 represents the stamping punch in a view XVI according to FIG.14.

FIG. 17 represents the region B according to FIG. 15 in enlargedrepresentation.

FIG. 18 represents the functional unit formed from a clamping screw, thepressure piece and a holding screw, in a three-dimensionalrepresentation.

FIG. 19 represents the functional unit in a view XIX according to FIG.20.

FIG. 20 represents the functional unit in a view XX according to FIG.19.

FIG. 21 represents the holding screw in a three-dimensional view.

FIG. 22 represents the holding screw in a view XXII according to FIG.23.

FIG. 23 represents the holding screw in a view XXIII according to FIG.22.

FIG. 24 represents the clamping screw in a three-dimensional view.

FIG. 25 represents the clamping screw in a view XXV according to FIG.26.

FIG. 26 represents the clamping screw in a view XXVI according to FIG.25.

FIG. 27 represents the pressure piece in a three-dimensional view.

FIG. 28 represents the pressure piece in a view XXVIII according to FIG.29.

FIG. 29 represents the pressure piece in a view XXIX according to FIG.28.

FIG. 30 represents for a second embodiment a modified stampingarrangement in a sectional representation according to FIG. 7.

FIG. 31 represents in a three-dimensional view the pressure piece shownin FIG. 30.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

FIG. 1 shows the top side of a “prog die” stamping unit 1 which isprovided with a multiplicity of forming punches, specifically eighteenforming punches. These are mounted in a common unit, which, in small tomedium size, has dimensions of about 1,600×1,200 mm. This stamping unit1 is mainly used in automobile construction, in particular in themanufacture of chassis and bodywork.

From FIG. 1 it can be seen that the eighteen forming punches arearranged spatially close together, surrounded by piping 3, which servesto monitor the pressures of built-in gas pressure springs 4 by means ofmanometers built into the tool.

Three of the forming punches which are used in the stamping unit 1 areconfigured in accordance with the a first exemplary embodiment of astamping arrangement 2 according to the invention.

This stamping arrangement 2 according to the first embodiment isillustrated in FIGS. 2 to 29.

The stamping arrangement 2 has a stamping punch 5 and a holding plate 6for the stamping punch 5. The stamping punch 5 has a punch part 7, bymeans of which the actual stamping is realized, as well as a punch head8 connected to the punch part 7. The punch head 8 is of plate-likeconfiguration. On the side facing toward the punch head 8, the punchpart 7 has a punch shoulder 9.

Between the stamping punch 5, specifically the punch shoulder 9, and theholding plate 6 is arranged a pressure plate 10. The pressure plate 10has a long hole 11 which passes through it. On both sides of the longhole, the pressure plate is provided with recesses for the reception ofscrews 12, wherein the (non-illustrated) heads of these screws 12 aresunk in the region of the bottom side of the pressure plate 10. By meansof these screws 12, the pressure plate 10 is fastened to the bottom sideof the holding plate 6, specifically is screwed into the threaded bores13 which are present there. The long hole 11 has such dimensions thatthe punch head 8 passes through the pressure plate 10 with low play inthe two spatial coordinates running perpendicular to the direction ofinsertion of the punch head 2.

Viewed in the direction of stamping, the holding plate 6, the pressureplate 10 and the punch part 7 have an identical cross-sectional shape,namely in the form of a rectangle with beveled corners. The surfaceareas of holding plate 6 and pressure plate 10, viewed in the directionof stamping, are equal, while the surface area of the punch part 7 inthis direction is smaller.

The holding plate 6 has in the region of the four corners bores for thereception of screws 14, wherein the respective screw head, on that sideof the holding plate 6 that is facing toward the pressure plate 10, issunk in a recess. By means of these screws 14, the holding plate 6 isconnected to a base plate 15 of the stamping unit 1. Two dowel pins 16mounted in the holding plate 6 serve for the guidance of the holdingplate 6 in the positioning of the holding plate 6 with respect to thebase plate 15. Correspondingly, the base plate 15 is provided not onlywith threaded bores for the screwing-in of the screws 14, but also withreceptacles for the insertion of the dowel pins 16.

The holding plate 6 has two receptacles 17 and an intervening crosspiece18. In this case, the receptacles 17 pass through the holding plate 6,while the crosspiece 18 extends only roughly over half of the thicknessof the holding plate 6, in that region of the holding plate 6 that isfacing away from the pressure plate 10. Correspondingly, the punch head8 has two head portions 19, between which a recess 20 is formed. Therespective head portion 19 is inserted into a receptacle 17 assignedthereto. In this case, the crosspiece 18 passes through the recess 20.Consequently the stamping punch 5 is positioned in the region of thepunch head 8 in the two coordinate directions perpendicular to thedirection of stamping, largely without play, in the receptacles 17 ofthe holding plate 6, and is also oriented with respect to the crosspiece18 of the holding plate 6.

In that position of the stamping punch 5 in which it is inserted in theholding plate 6 and in which the stamping punch 5 passes with the punchhead 8 through the pressure plate 10 and the pressure plate 10 isscrewed to the holding plate 6 and this is screwed to the base plate 15of the stamping unit 1, said components form a functional unit. In thiscase, the stamping punch 5 bears in the direction of stamping in aplay-free manner against the pressure plate 10 in the region of thepunch shoulder 9.

Owing to the described arrangement, the stamping punch 5 can be removedor exchanged without the need for removal of the pressure plate 10 fromthe holding plate 6.

The stamping punch 5 is held in the holding plate 6 by doubly providedmeans 21 for fastening the punch head 8 to the holding plate 6. Therespective means 21 has a pocket 22 made in the punch head 8, a clampingscrew 24 screwed into a threaded bore 23 of the holding plate 6, apressure piece 25 arranged in the axial direction of the clamping screw24 between the latter and the pocket 22, and a holding screw 26 for thepressure piece 25. The holding screw 26 passes through a bore 27 of theclamping screw 24 and is screwed with a threaded portion 28 into athreaded bore 29 of the pressure piece 25. In a screwed-in position ofthe clamping screw 24, on a side 30 of the pocket 22 that is facing awayfrom the punch shoulder 9, a conical portion 31 of the pressure piece 25makes full-faced contact with a conical portion 32 of the pocket 22. Inthis screwed-in position of the clamping screw 24, illustrated in detailin FIG. 7, the punch shoulder 9 bears squarely against the pressureplate 10. In this case, a screw head 33 of the holding screw 26 isarranged with axial play, illustrated by the gap 34, with respect to theclamping screw 24.

In detail, that end of the pressure piece 25 that is facing away fromthe pocket 22 is configured as a rotationally symmetrical cylinder 35and that end of the pressure piece 25 that is facing toward the pocket22 is configured as a truncated cone 46. A peripheral region of thetruncated cone 46 has in the region of its free end a flat contactsurface 36 for the purpose of contact with the pocket 22. The pocket 22is configured as a frustoconical recess, tapering in the direction of afloor 37 of the pocket 22 and having a flat contact surface 38, disposedat least in a peripheral region of the truncated cone, for the purposeof full-faced contact with the contact surface 36 of the pressure piece22. In this case, the pocket 22, thus the frustoconical recess, has anoval, in particular slightly oval cross section. The extent of thepocket 22 transversely to the direction of stamping of the stampingpunch 5 or in the return direction thereof is less than the extent ofthe pocket 22 perpendicular to this direction. This allows a certaintolerance compensation in the transverse extent, thus in the directionof the distance apart of the two pockets 22, from the aspect ofproduction inaccuracies.

Solely for reason of simplified production, on the conical part of thepressure piece 25 there is likewise provided, also in the diametralregion, a face 39.

As can be seen in particular from FIG. 7, the pressure piece 22, in thescrewed-in position of the clamping screw 24, is arranged at a distanceto the floor 37 of the pocket. The clamping screw 24 has a screw head 40having an outer polygon, configured as a hexagon. In the screwed-inposition of the clamping screw 24, the screw head 40 protrudes beyondthe holding plate 6, so that, without the need for considerableinstallation space next to the stamping arrangement 2, simple actuationof the screw head 40 by means of a screwing tool is possible. Theholding screw has a screw head having an inner polygon, in particular ahexagon, wherein the screw head 41 is disposed within the clamping screw24.

FIG. 2 shows one clamping screw 24 in its screwed-in position (inaccordance with FIG. 7) and the other clamping screw 24 in a partiallyunscrewed position (in accordance with FIG. 8).

In the stamping arrangement 2, two pockets 22 are thus made in the punchhead 8, and a pressure piece cooperates with the respective pocket 22,and a clamping screw 24 and a holding screw 26 cooperate with thepressure piece 25. The pockets 22 are identically configured, just asthe clamping screws 24 are identically configured, the pressure pieces25 are identically configured, and the holding screws 26 are identicallyconfigured.

In the stamping arrangement 2 according to the invention, the stampingpunch 5 is placed through the pressure plate 10 and screwed to theholding plate 6. The precise location positioning is realized by twofits in the X and Y direction. By the two means 21, the stamping punch 5is secured against being pulled out in the Z direction. This type ofsecurement or fastening enables rapid changing of the stamping punch 5.In the clamped state, as is illustrated in particular in FIG. 7, therespective pressure piece 25 bears against the end face of the clampingscrew 24 and is pressed via its external thread into that milled recessin the punch head 8 which corresponds to the geometry of the pressurepiece 25. Via the bevel on the end of the pressure piece 25, the punchshoulder 9 is drawn against the pressure plate 10 by means of thecounter bevel in the punch head 8, so that the stamping punch 5 can bepressed by means of the two provided means 21, counter to the directionof stamping, with pretension against the pressure plate 10, which canthen absorb the stamping pressure.

For the removal of the stamping punch 5 in the direction of stamping,the respective clamping screw 24 is loosened and, following contact ofthe bottom part of the screw head 41 of the holding screw 26 for thepressure piece 25 with the countersink in the clamping screw 24, thepressure piece 25 is pulled by means of the holding screw 26 out of themilled recess in the punch head 8. Upon further rotations of theclamping screw 24, the pressure piece 25 frees the stamping punch 5,specifically the punch head 8, after the pressure piece 25 is movedcompletely out of the punch head 8.

A further function of the clamping screws 24 is the absorption of thestripping pressure following stamping when the stamping punch 5 leavesthe stamped sheet in the direction of the upper dead center. This iseffected by the pressing of the respective head portion 19 against theopposite wall of the receptacle of the holding plate 6 by means of theclamping screws 24, and by the shearing resistance of the cross sectionof the engaged pressure pieces 25.

The forces which arise in the course of the stripping after the stampingcan in this case amount to up to 100 kN.

The use of a plurality of clamping screws, in the present case the twoclamping screws 24, enables narrow tolerance ranges to be managed bothin the series arrangement of the clamping screw threads in respect ofthe holding plate 6, and of the milled recesses in the punch head 8, bywhich bevels in the milled recess in the punch head 8 and also on thefront part of the pressure piece 25 are compensated without impairmentof a clamping screw 24 in terms of its function of pressing the punchshoulder 9.

The clamping screw 24 is constituted, for instance, by a M16 screw, theholding screw 26 by a M4 screw. The pressure piece has, for instance, adiameter of 13 mm, wherein the conical portion 31 runs at an angle of 5°to the pocket axis. The oval conical pocket 22 has, for instance,dimensions of 14 mm/12 mm, with a 6 mm depth.

A second exemplary embodiment according to FIGS. 30 and 31 differs fromthe first embodiment only in terms of the configuration of the pressurepiece 25 and means for the loose precentering of the pressure piece 25.In this respect, for the avoidance of repetitions, reference is made tothe basic statements concerning the first embodiment.

In the second embodiment according to FIGS. 30 and 31, the cylindricalportion 35 of the pressure piece is provided with a groove 42 which runsin the axial direction and is open radially outward. This groove extendsfrom that end of the pressure piece 25 that is facing away from thecontact surface 36 to almost into the region of the contact surface 36.The groove 42 is arranged such that the extension of the groove 42coincides with a line of symmetry of the contact surface 36, so that anorientation of the groove 42 corresponds to a corresponding orientationof the contact surface 36. Cooperating with the groove 42 is a setscrew43, which in the region of its end facing toward the pressure piece 25has a dog point 44. The diameter of the dog point 44 is slightly smallerthan the width of the groove 42. The setscrew 43 is screwed into athreaded bore 45 of the holding plate 6. The setscrew 43 with dog point44 enables a loose precentering of the pressure piece 25. It can thuseasily be ensured that, when the clamping screw 24 is screwed in, thepressure piece 25, in the region of its contact surface 36, is exactlyoriented with respect to the conical portion 32 in the pocket 22.

In the preassembly of the holding plate 6, the respective pressure piece25 is oriented once with its groove 42 and the setscrew 43 is screwed into the point where its dog point 44 engages in the groove 42 without atensioning between the dog point 44 and the pressure piece 25. Thepressure piece 25 is thus fixed with play. Neither the groove 42, northe turned end of the setscrew 43, i.e. the dog point 44, are subjectedto load, since the precentering function is fulfilled with the threadingof the faces of the pressure piece 25 into the associated pocket 22 inthe holding plate 6.

1. A stamping arrangement having a stamping punch and a holding platefor the stamping punch, wherein the stamping punch, in a stampingstroke, makes contact in the region of a punch shoulder with the holdingplate, or with a pressure plate disposed between the stamping punch andthe holding plate, and the stamping punch has a punch head and theholding plate has a receptacle for the punch head, and means forfastening the punch head to the holding plate are provided, wherein themeans have: a pocket made in the punch head, a clamping screw screwedinto a threaded bore of the holding plate, a pressure piece arranged inthe axial direction of the clamping screw between the clamping screw andthe pocket, and a holding screw for the pressure piece, wherein theholding screw passes through a bore of the clamping screw and is screwedwith a threaded portion into a threaded bore of the pressure piece,wherein, in a screwed-in position of the clamping screw, on a side ofthe pocket that is facing away from the punch shoulder, a conicalportion of the pressure piece makes full-faced contact with a conicalportion of the pocket, and, in this screwed-in position of the clampingscrew the punch shoulder bears against the holding plate or the pressureplate, and a screw head of the holding screw is arranged with axial playwith respect to the clamping screw.
 2. The stamping arrangement asclaimed in claim 1, wherein an end of the pressure piece that is facingtoward the pocket is of frustoconical configuration, and a peripheralregion which is present there, in the region of its free end, has aflattened contact surface for the purpose of contact with the pocket. 3.The stamping arrangement as claimed in claim 2, wherein the pocket isconfigured as a frustoconical recess, tapering in the direction of afloor in the pocket and having a contact surface, disposed in aperipheral region for the purpose of contact with the pressure piece. 4.The stamping arrangement as claimed in claim 3, wherein thefrustoconical recess defined by the pocket has an oval cross section. 5.The stamping arrangement as claimed in claim 3, wherein the pressurepiece, in the screwed-in position of the clamping screw, is arranged ata distance to the floor of the pocket.
 6. The stamping arrangement asclaimed in claim 1, wherein means for orienting the pressure piece in arotational direction of the pressure piece relative to the conicalportion of the pocket are provided.
 7. The stamping arrangement asclaimed in claim 1, wherein the clamping screw has a screw head havingan outer polygon for cooperating with a screwing tool.
 8. The stampingarrangement as claimed in claim 7, wherein the screw head of theclamping screw, in the screwed-in position of the clamping screw,protrudes beyond the holding plate.
 9. The stamping arrangement asclaimed in claim 1, wherein the screw head of the holding screw has aninner polygon, and wherein the screw head is disposed within theclamping screw.
 10. The stamping arrangement as claimed in claim 1,wherein the pressure plate is connected to the holding plate and isprovided with a long hole which passes through the punch head.
 11. Thestamping arrangement as claimed in claim 1, wherein two pockets are madein the punch head, and a corresponding pressure piece cooperates with arespective pocket, and a clamping screw and a holding screw cooperatewith the corresponding pressure piece.
 12. The stamping arrangement asclaimed in claim 11, wherein the pockets are identical, the clampingscrews are identical, the pressure pieces are identical, and the holdingscrews are identical.
 13. The stamping arrangement as claimed in claim1, wherein the holding plate has two receptacles and the punch head hastwo head portions, wherein a respective head portion is inserted into arespective receptacle and each head portion has a pocket.
 14. Thestamping arrangement as claimed in claim 1, wherein the punch head isguided in the holding plate in the spatial directions arrangedperpendicular to the direction of insertion into the holding plate. 15.Use of the stamping arrangement as claimed in claim 1 in a stamping unitwith a stripping force per stamping punch greater than about 50 kN andless than about 100 kN.